I have a Kindle 1, so it's not got the same features as what's available now on the Kindle 2 and the Kindle DX, but the the K2 and the KDX both have a nice feature where you can have the Kindle read your book to you. (considered an experimental feature, and it's not enabled for all books. Some publishers dont have it activated for their books)

I've had a few vision problems, and love that I can change the font sizes on my Kindle. Didnt help much when I had double vision earlier this year, but it helps at other times.

The way the Kindle downloads is thru the Sprint 3G cellphone network. (which you're not charged for) It takes about a minute to get a book downloaded, depending on where you are. If you're in an area that doesnt get Sprint, you can use your computer to download the book and transfer it to the Kindle with a USB cord. (probably always a good idea to back up your Kindle library on the computer anyways)

My Kindle probably holds more than the Kindle 2 does, since my Kindle has the option of using an SD card inside the Kindle for storage. I think the Kindle 2 holds up to about 1500 books. The KDX has a larger amount of onboard memory, but I dont remember how many books it holds.

I think my Kindle 1, without the card, holds about 1500 books. (I'm no where near that amount of reading material yet) I have a 4gb SD card in mine, so that probably increases what it can hold a lot.

You can download music and audiobooks to the Kindles also. With my Kindle, using headphones is annoying, because they put spot to plug headphones in the bottom of the unit. The K2 has the headphone jack in the proper spot on the top. (my dad has a K2, I should put some music on his and see how it sounds) The music playing ability is pretty basic, you have to use the keyboard and the CTRL button to control the music, but if you're just going to sit and read and listen to music, it's not too bad. Not an iPod, but at least with mine, the sound quality is pretty good thru headphones.

The screen is not backlit, so it's easier to read, not as harsh on the eyes as something backlit, like when I used to read on my PDA screen. The Kindle uses E-Ink technology. It's really cool. But, because it's not backlit, you need light to read it. But, collecting booklights that clip onto books is fun. You should see people on the Kindle forums, collecting covers for their Kindles, purses, skins (decals that you can decorate the Kindles with) It's actually kind of fun if you're into doing stuff like that. I'm one of the people who collect purses and cases for my Kindle.

So far as I know, to read your books, you HAVE to read them on the Kindle. I think there are people that have figured out how to hack the DRM (Digital Rights Management) and unlock the books to read on computers, but I dont know how difficult that is. It would be nice to be able to read the books in other digital/electronic formats too, so maybe someday Amazon will figure out a way for people to put the books on their computers without being too jerky about giving up the DRM (and hopefully the Author's Guild wouldnt be too sucky about it either. They're part of the reason that the Text To Speech function is disabled on the Kindle 2 for a lot of books...they whined and said the TTS was doing "performances". I thought the TTS would be great for people with vision problems. The TTS is one of the biggest reasons I want a Kindle 2 now)

The Kindle has a few limitations, but I still love mine. I still like real books too, but I'm really liking my Kindle right now while my left hand is a bit screwed up by the MS. My Kindle 1 is easy to hold, it's light, (have you read a Harry Potter book lately. Those books are heavy! even if you get the paperbacks! HP isnt available on the Kindle yet...) The Kindle has nice big Next Page buttons that I dont need a lot of coordination to press. It cant read to me like the Kindle 2 can, but it's so comfortable to read. I really do enjoy reading books on my Kindle.

When I go to the gym to walk on the treadmill, I take my Kindle with me. It sits on the little book ledge on the treadmill and I walk and read. I love that I dont have to fumble around with pages blowing around, and I can increase or decrease the text size of the words. It made the tediousness of walking on a treadmill a lot more fun. I cant wait till my MS flare is over so that I can get back to doing that again.